TurboTax will use your personal information that you provided last year to update your 2017 return. This saves time, because you will not need to re-enter all your personal information again such as your address, phone number, etc. You will be provided an opportunity to review the data that was used from last year's form and provide any required updates. TurboTax also transfers any carryovers, depreciation and other necessary information from last year's forms. Bottom line is that it saves you a lot of time.